UNIVERSITY   OF   CALIFORNIA 

COLLEGE   OF   AGRICULTURE 

AGRICULTURAL   EXPERIMENT   STATION 

BERKELEY,    CALIFORNIA 

CIRCULAR  312 

March,  1928 

PRINCIPLES  GOVERNING  THE  CHOICE, 

OPERATION  AND  CARE  OF  SMALL 

IRRIGATION  PUMPING  PLANTS 

C.  N.  JOHNSTONi 


INTRODUCTION 

The  development  of  agriculture  in  California  depends  almost 
entirely  upon  the  progress  made  in  irrigation.  Many  thousands  of 
acres  in  the  state  would  be  unavailable  for  growing  the  crops  giving 
the  higher  returns,  were  it  not  for  the  water  supplied  by  irrigation 
pumping  plants.  All  of  the  standard  types  of  pumps  are  used  to 
some  extent  in  irrigation.  The  four  outstanding  types  now  in  use  for 
irrigation  are  the  centrifugal,  the  deep  well  turbine,  the  screw,  and 
the  plunger.  Air-lift  and  rotary  displacement  pumps  are  found 
occasionally,  and  serve  only  small  irrigated  areas. 


GENERAL   DISCUSSION    OF    PUMPS 

Pumping  for  irrigation  dates  back  to  the  beginning  of  history 
when  men  or  beasts  of  burden  supplied  the  power  that  moved  water 
by  one  means  or  another.  Many  machines  were  developed  in  Egypt 
and  India  for  this  purpose  long  before  the  age  of  mechanical  power ; 
today  some  of  these  are  used  in  modified  form  in  California.  With 
the  invention  of  the  steam  engine  and  the  demands  made  by  coal-mine 
owners  for  better  pumping  machinery  late  in  the  eighteenth  century, 
progress  in  the  mechanical  powering  of  pumps  began.  Since  this 
time  the  use  of  mechanical  power  as  applied  to  pumps  has  increased 
rapidly.    Today  in  California  about  one-sixth  of  the  electrical  power 


Junior  Irrigation  Engineer  in  the  Experiment  Station.     Eesigned  July  16,  1926. 


Z  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

produced  in  the  state  is  consumed  in  driving  irrigation  pumping 
equipment.  This  does  not  take  into  consideration  the  pumps  driven 
by  fuel-oil  engines. 

Pumping  originally  consisted  of  filling  some  sort  of  container  or 
carrier  by  immersion  in  a  body  of  water  and  then  transporting  the 
retained  water  to  a  higher  elevation.  Some  pumps  use  this  process 
today.  Others  are  not  immersed  in  the  source  of  supply  at  all  but 
are  connected  with  it  through  a  suction  pipe  only.  In  these  instances 
the  operation  of  the  pump  creates  a  reduction  of  pressure,  or  partial 
vacuum,  within  itself,  causing  the  water  at  the  source  to  be  forced 
into  the  pump  by  the  greater  pressure  of  the  air  outside.  The  amount 
of  vacuum  or  reduction  in  pressure  that  must  be  produced  in  order 
to  raise  the  water  to  the  pump  is  roughly  equal  to  the  pressure  that  is 
produced  by  a  column  of  water  equal  in  height  to  the  vertical  distance 
between  the  center  of  the  pump  and  the  surface  of  the  supply  water. 
A  perfect  vacuum  is  a  total  lack  of  pressure,  and  if  such  a  condition 
is  created  in  a  pump,  the  water  will  rise  from  the  source  a  vertical 
distance  of  about  34  feet,  at  sea  level.  This  distance  decreases  as  the 
elevation  above  sea  level  increases,  because  the  weight  of  air  diminishes 
with  increase  of  elevation.  It  is  not  desirable  to  place  an  irrigation 
pump  more  than  15  to  20  feet  above  the  water  source,  because  friction 
in  the  suction  pipe  consumes  some  of  the  pressure  difference  created 
by  the  pump  when  in  operation. 

Every  mechanical  contrivance  wastes  a  certain  amount  of  power 
within  itself  in  the  performance  of  its  task;  this  is  of  course  true  of 
all  pumping  equipment.  The  power  delivered  by  pumping  equipment 
divided  by  the  power  supplied  to  it  gives  a  ratio  which,  when 
expressed  as  a  percentage,  is  known  as  the  efficiency  of  the  plant.  In 
other  words,  the  efficiency  of  a  pumping  plant  is  a  measure  of  its 
behavior  while  in  operation.  When  the  efficiency  is  low,  the.  pumping 
cost  is  higher  than  it  should  be,  because  more  power  is  being  wasted 
than  is  necessary. 

Pumps  located  above  the  source  of  water  supply  must  be  capable 
of  'drawing'  the  water  to  them  when  they  are  started  empty,  or  if 
incapable  of  so  doing,  both  the  pumps  and  the  suction  lines  must  be 
filled  with  water  previous  to  starting;  that  is,  they  must  be  primed. 
This  is  accomplished  by  the  use  of  a  hand  pitcher-pump  or  equivalent 
power-driven  unit,  connected  to  the  highest  point  of  the  pump  case, 
by  means  of  which  the  air  is  withdrawn  from  the  pump  and  suction 
pipe.  The  discharge  valve  being  closed  during  this  operation,  the 
water  rises  from  below  and  replaces  the  air  as  the  latter  is  withdrawn. 


CIRC.  312 J      OPERATION  OF  SMALL  IRRIGATION   PUMPING  PLANTS  3 

Or,  the  priming  may  be  accomplished  by  filling  the  pump  and  suction 
pipe  with  water  from  some  available  supply,  a  flap  valve  being  located 
at  the  bottom  of  the  suction  pipe  to  prevent  the  loss  of  the  priming 
water.  When  the  first  method  is  used,  the  discharge  valve  is  opened 
automatically  or  by  hand  as  soon  as  the  pump  is  started.  If  the 
second  is  used,  the  flap  valve,  or  foot  valve,  opens  automatically  as 
soon  as  the  pressure  of  water  above  is  relieved.  Pumps  whose  operat- 
ing parts  are  submerged  in  the  source  of  supply  require  no  priming. 


CENTRIFUGAL    PUMPS 

The  types  of  pumps  used  in  irrigation  in  California  obtain  their 
names  largely  from  their  method  of  applying  power  to  the  task  of 
moving  water.  Of  the  chief  types  used  for  irrigation,  the  centrifugal 
was  the  first  produced  in  this  country,  having  appeared  in  Boston 
in  1817.  It  was  called  the  Massachusetts  pump  and  was  made  very 
crudely.  It  had  as  an  impeller  four  straight  paddles  or  vanes,  which 
have  been  replaced  in  the  modern  pump  by  the  curved  vanes,  forming 
smooth  passages  for  the  water.  Its  principle  of  operation,  however, 
was  the  same  as  that  of  the  present-day  centrifugal  pump,  the  water 
in  both  cases  being  forced  through  openings  in  the  impellers  by 
centrifugal  action  caused  by  their  high  speed  of  rotation.  In  the 
centrifugal  pump,  in  other  words,  as  the  water  is  thrown  out  of  the 
impeller  it  creates  the  partial  vacuum  necessary  to  draw  in  more 
water  and  thus  continue  the  operation. 

Centrifugal  pumps  may  be  obtained  to  operate  against  low  or 
high  lifts,  and  to  discharge  almost  any  desired  quantity  of  water. 
When  they  have  been  purchased  to  fit  the  operating  conditions,  they 
show  very  good  efficiencies.  Because  these  pumps  are  accessible  at 
all  times  and  can  be  inspected  and  kept  in  repair,  the  efficiency  may 
be  maintained  indefinitely  unless  the  impellers  are  subject  to  excessive 
wear  from  abrasive  material  in  the  water. 

The  cases,  or  housings,  of  these  pumps  are  supplied  either  as  solid 
or  as  split  castings  (fig.  1).  The  solid  type  has  a  plate  bolted  on  the 
side,  which,  when  taken  off,  permits  the  removal  of  the  shaft  with  the 
impeller  on  it.  The  split  type  opens  on  the  center  line  of  the  shaft, 
exposing  bearings,  shaft,  and  impeller.  In  either  case,  the  impellers 
may  be  of  the  open  or  closed  type.  The  former  type  is  more  common 
with  the  single-suction  solid-case  pumps.  Open  impellers,  as  the  name 
implies,  are  simply  impeller  vanes  mounted  or  cast  against  one  disk 
or  hub.    Closed  impellers  have  their  vanes  mounted  between  two  disks. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

They  provide  better  guidance  for  the  water  than  the  open  type  and 
are  generally  more  efficient. 

The  suction-pipe  connections  in  these  two  types  differ,  as  a  rule. 
In  the  solid-case  pump,  the  suction  pipe  enters  the  center  of  one 
side  of  the  case,  so  that  the  water  passes  into  the  center,  or  throat, 
of  the  impeller  on  one  side  only.  In  the  split-case  pump,  the  suction 
line  is  in  the  same  plane  as  the  impeller,  at  right  angles  to  the  shaft, 
and  the  pump  casing  is  so  built  as  to  lead  the  water  around  both  sides 


Fig.  1. — Typical  pumps.  (1)  Split-shell  centrifugal  pump  opened  for  inspec- 
tion; (2)  single-suction  centrifugal  pump  opened  for  inspection;  (3)  deep  well 
turbine  model  with  runners  and  shaft  exposed,  full-sized  bowls  and  runner 
being  shown  in  front;  (4)  single  screw  from  deep  well  pump;  (5)  rotary  dis- 
placement priming  pump.      (The  pump  appears  just  above  the  number.) 


CIRC.  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS  5 

of  the  case  into  the  two  throats  of  the  impeller.  Double  entry  of  the 
water  into  the  impeller  tends  to  balance  the  thrust  of  the  water  stream 
entering  it — a  considerable  advantage  for  this  type  of  construction 
not  usually  obtained  in  the  single-suction  pump.  Previously  the 
solid-case  pumps  were  often  made  with  two  suction  pipes,  accom- 
plishing the  same  result  as  the  present  split-case  pump  with  its 
divided  channels  within  the  case.  Special  thrust  bearings  are  fre- 
quently placed  in  both  types  of  pumps  to  take  up  any  unbalanced 
forces  on  the  impellers. 

The  losses  in  efficiency  in  centrifugal  pumps  are  attributable  to 
air  leaks,  water  slippage,  and  undue  churning  of  the  water.  The  first 
cause  may  be  eliminated  through  occasional  inspection  of  the  packing 
glands  and  suction-line  connections.  The  second,  in  so  far  as  possible, 
is  taken  care  of  by  correct  design,  all  passageways  that  can  permit 
leakage  between  discharge  and  inlet  of  the  impellers  being  made  as 
narrow  as  possible,  and  in  some  cases  being  made  extra  long  by  the 
insertion  of  grooved  rings.  For  this  reason,  an  impeller  should  not 
be  allowed  to  rub  on  the  side  of  the  case  because  of  the  resulting  wear, 
which  is  accompanied  by  excessive  internal  leakage.  Churning,  the 
third  cause  of  low  efficiency,  is  the  natural  result  of  operation  and 
may  be  corrected  only  in  part  by  proper  design  and  correct  speed  of 
rotation.  This  last  factor  is  especially  important  because  the  cen- 
trifugal pump  is  designed  to  operate  at  a  given  rotative  speed  against 
a  given  lift,  and  to  throw  a  predetermined  quantity  of  water.  When 
the  speed  is  changed,  therefore,  from  that  for  which  it  is  designed, 
the  pump  cannot  show  its  best  performance.  Churning  often  arises 
where  the  pumping  lift  has  remained  constant  and  the  discharge  has 
been  increased  by  raising  the  speed  of  rotation  of  the  pump  consider- 
ably above  the  rated  number  of  revolutions  per  minute. 

As  has  been  previously  stated,  irrigation  pumps  not  immersed  in 
the  supply  source  should  be  located  not  more  than  15  to  20  feet  above 
that  source,  and  for  this  reason,  as  the  water  level  recedes,  the  pumps 
must  be  lowered  or  they  cease  to  operate.  In  most  cases  when  cen- 
trifugal pumps  are  used  to  lift  water  from  wells,  they  must  be  set 
in  pits  at  the  time  of  installation.  These  pits  are  expensive  to  con- 
struct and  are  often  dangerous.  It  is  desirable  to  make  them  as 
small  as  possible.  For  these  and  other  reasons,  centrifugal  pumps 
have  been  developed  with  vertical  shafts  which  permit  their  operation 
from  the  ground  surface.  Pumps  with  long  shafts  which  are  often 
used  in  deep  pits,  however,  are  subject  to  much  trouble,  and,  conse- 
quently have  been  largely  replaced  by  the  deep  well  turbine  and 
other  true  deep  well  types. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


DEEP  WELL  TURBINE   PUMPS 

The  turbine  pump  is  a  form  of  the  centrifugal,  in  which  the  pump 
case  contains  stationary  curved  diffusion  vanes  that  lead  the  water 
away  from  the  impeller  to  the  discharge  opening  with  a  minimum  of 
turbulance,  receiving  the  water  from  the  impellers  at  high  velocity 
and  passing  it  on  with  reduced  velocity  and  increased  pressure.  Deep 
well  turbines  (fig.  1)  have  been  developed  to  meet  the  requirements 
associated  with  pumping  from  wells  of  limited  diameter.  They  are 
built  to  operate  on  a  vertical  shaft  with  a  single  unit  or  bowl,  or  with 
several  mounted  in  series,  one  above  the  other,  the  stationary  curved 
vanes  in  the  case  turning  the  water  from  the  impeller  upward  to  the 
bowl  above,  or  to  the  discharge  column  pipe. 

Because  this  form  of  pump  is  limited  in  size  by  the  well  it  must 
enter,  it  is  necessary  to  forfeit  part  of  the  good  characteristics  of 
operation  possible  in  the  centrifugal  or  turbine  not  so  limited,  but 
giving  an  equivalent  discharge.  For  instance,  under  present  practice, 
the  deep  well  turbine  may  be  operated  against  a  head  of  about  25  feet 
per  bowl,  or  stage,  whereas  the  centrifugal  or  turbine  designed  for 
use  outside  a  pit  may  be  capable  of  operating  at  triple  this  head  per 
stage.  This  is  the  reason  for  mounting  several  bowls  in  a  series  in  a 
deep  well  turbine  when  the  pumping  lift  is  more  than  25  feet.  The 
present  tendency  in  design  is  for  higher  rotative  speeds,  resulting 
in  higher  heads  and  greater  discharge  capacities  per  bowl.  The  deep 
well  turbine  is  always  mounted  with  the  bowls  below  the  surface  of 
the  standing  water  in  the  well,  so  that  it  is  always  ready  to  operate 
without  priming.  This  distinct  advantage  is  offset,  however,  by  the 
fact  that  these  rapidly  rotating  parts  are  buried  in  the  well,  and  very 
often  receive  no  attention  until  they  fail  to  operate.  Since  minor 
adjustments  are  likely  to  be  needed  in  any  mechanism  that  rotates 
at  high  speed,  the  efficiency  of  the  deep  well  turbine  is  often  lowered 
because  repairs  are  not  made,  owing  to  the  inaccessibility  of  its 
moving  parts. 

Considerable  difficulty  arises  from  the  fact  that  power  for  the  deep 
well  turbine  must  be  transmitted  through  a  long  shaft.  Manufacturers 
have  adopted  many  expedients  for  overcoming  this  difficulty.  Some 
pumps  have  enclosed  drive  shafts,  in  which  the  bearings  of  bronze 
or  other  special  material  are  mounted,  while  others  eliminate  the 
bearings  entirely  and  provide  wooden  guides  which  extend  practically 
the  whole  length  of  the  shaft,  to  prevent  flopping  or  whipping.   Others 


ClRO.  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS  7 

accomplish  the  same  result  by  placing  rubber  guides  or  bumpers  at 
intervals  along-  the  otherwise  exposed  shaft.  These  do  not  require 
oiling  (fig.  2). 

The  lubrication  necessary  to  these  long  drive  shafts,  which  are 
mounted  on  bearings,  is  accomplished  by  several  means.  Some  shafts 
are  made  hollow  in  order  to  carry  oil  to  the  bearings;  others  use  the 
drive-shaft  housing  for  this  purpose.  The  bottom  bearing  of  the 
deep  well  turbine  is  of  such  great  importance  that  a  special  line  is 


Pump 
co/umn 


Open  bearing  in 
spider  frame  screwed 
info  pump  co/umn 


fnc/osed  metu/lic 
bearing  joining  fyvo 
sections  of  drive  shaft 
bousing 

Drive  shaft  bousing 


Drive  sbofl,  no  bearings 

■Dpi 'it  yyood  liner  yvitb 
bo/byv  core  for  s-faft 

Metallic  bousing  for 
liner  and  drive  shaft 


or 


-H 


£bbber  beo'W 
bumper 


Metallic  spider  frame 

screwed  into  pump 
"column  and  supporting 


Fig.   2. 


-Various  types  of  shaft-bearing  construction   for  deep  well 
turbine  pumps. 


sometimes  run  down  outside  the  pump  to  effect  its  lubrication.  In 
other  instances,  the  bearing  is  packed  with  grease  when  assembled 
and  is  repacked  only  when  repairs  become  necessary.  Since  all  of 
these  devices  are  liable  to  failure,  they  should  be  inspected  whenever 
possible.  Rapid  deterioration  of  bearings  often  results  from  gritty 
materials  which  are  contained  in  the  water  being  pumped  and  which 
become  mixed  with  the  lubricating  oils. 

These  turbine  pumps  may  be  purchased  for  either  belt  or  direct 
connection  to  the  power  unit  for  lifting  water  any  desired  distance. 
Some  installations  at  present  approach  lifts  of  500  feet.  When  kept  in 
good  condition  mechanically,  they  operate  with  very  good  efficiency. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


SCREW-TYPE    PUMPS 

The  screw-type  pump  is  an  application  of  the  principle  used  by 
Archimedes  to  move  water  upward  on  an  inclined  plane  turning  on 
a  movable  shaft.  There  are  several  types  of  the  screw  pumps  in  use 
in  irrigation.  All  involve  fundamentally  a  rapidly  rotating-  section 
of  an  inclined  plane,  although  some  have  several  planes  on  a  common 
hub.  Their  action  in  water  is  the  same  as  that  of  an  electric  fan  in 
air,  which  slides  the  air  forward  from  its  rotating,  inclined  vanes 
(fig.  1).  Some  are  used  for  heads  of  less  than  10  feet,  moving  large 
quantities  of  water ;  others  are  used  for  medium  to  high  lifts  in  wells. 

The  low-lift  screw  pump  falls  into  two  classes,  those  whose  drive 
shafts  are  horizontal  and  those  whose  shafts  are  vertical.  The  units 
with  horizontal-drive  shafts  are  very  large  and  are  used  where  large 
quantities  of  water  are  to  be  raised  a  short  distance.  The  low-lift 
screws  on  vertical  shafts  are  mostly  smaller-capacity  ditch  pumps, 
which  lift  the  water  a  few  feet  out  of  the  ditch  onto  the  land.  Some 
of  these  pumps  are  very  crudely  made,  being  merely  a  screw  mounted 
at  the  lower  end  of  a  shaft  enclosed  by  a  rectangular  housing  and 
supported  on  one  bearing  placed  at  the  top.  Their  efficiency  is  low, 
and  were  the  lift  greater  they  could  not  be  operated  at  all  because 
the  cost  of  power  would  be  too  high.  Other  designs  set  in  carefully 
planned  housings  and  having  substantial  bearings  show  very  good 
efficiencies,  and  because  of  their  simplicity,  are  readily  repaired  and 
kept  in  gcod  condition. 

The  deep-well  form  of  screw  pump  is  a  series  of  low-lift  pumps 
so  mounted  on  a  single  shaft  that  they  operate  as  a  unit.  They  are 
assembled  from  sections  about  6  feet  long.  Each  section  has  two 
screws  mounted  in  it  with  a  single  bearing  which  is  supported  in  a 
spider  frame  between  the  two  screws.  The  planes  of  the  spider  tend 
to  keep  the  water  from  whirling  as  it  travels  upward.  A  second  set 
of  vanes  is  placed  above  the  upper  screw  in  each  unit  to  stop  the 
whirling  action  of  the  water  leaving  that  screw.  When  it  is  desired 
to  pump  against  a  head  at  the  surface  of  the  well,  a  number  of  screws 
are  nested  at  the  bottom  of  the  pump  because  the  total  lift  per  screw 
cannot  exceed  about  4  feet  and  should  be  about  2x/2  to  3  feet,  under 
which  conditions  this  type  of  pump  operates  with  very  good  efficiency. 

Screw  pumps  are  subject  to  the  same  difficulties  as  the  deep  well 
turbines  with  their  long  shafts  transmitting  the  power.  Since  it  is 
impossible  to  line  the  drive  shaft  and  bearings  with  screws  located 


UlRC.  3 12 J      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS  9 

along  the  length  of  the  shaft,  the  bearings  are  open  to  the  entry  of 
abrasive  substances  in  the  water.  This  disadvantage  is  balanced  by 
the  adaptability  of  these  pumps  to  changing  water  tables,  because 
sections  of  pump  added  at  the  top  or  removed  from  the  top,  as  the 
conditions  dictate,  will  enable  the  pump  to  follow  the  water  levels. 
In  contrast,  the  turbine  requires  complete  withdrawal  for  changing 
the  bowls  whenever  a  lowered  or  raised  water  table  necessitates  it. 
As  in  the  case  of  the  turbines,  the  screw  pump  is  liable  to  be  operated 
when  repairs  should  be  made.  It  requires  no  priming,  since  the 
operating  parts  are  immersed  in  the  water  supply.  As  a  general  rule, 
screw  pumps  will  handle  more  water  than  deep  well  turbines  of  the 
same  outside  diameter. 


V/////////////////////////////////Z77Z7/. 


L 


Moving 
piston 


w//W////w//////////////////////mn 


V//////////A 

Discharge 

'////////////A 


^ZZZZZZZZ^ 


Joe  f ion 


'////////////A 


Fig.  3. — Simple  plunger  pump. 


PLUNGER    PUMPS 

The  plunger  pump  may  be  obtained  in  many  styles,  but  its  use  in 
irrigation  is  limited  by  the  fact  that  its  capacity  is  relatively  small. 
Fundamentally  all  plunger  pumps  are  pistons  sliding  in  close-fitting 
chambers  (fig.  3)  with  two  valves  so  arranged  that  one  opens  when 
the  piston  creates  a  partial  vacuum  in  the  chamber,  the  other  being 
forced  shut.  The  reverse  occurs  when  the  piston  creates  a  pressure 
in  the  chamber.  The  suction  line  connects  to  the  port  over  the  valve 
that  opens  under  vacuum  and  the  discharge  line  connects  to  the  port 
over  the  valve  opening  under  pressure  from  the  piston.  The  many 
designs  of  plunger  pumps,  both  power  and  deep-well  types,  are  all 
applications  of  the  fundamental  type  either  for  use  in  wells  or  for 
service  at  the  surface  of  the  ground. 

Deep  well  plunger  pumps  are  used  in  areas  where  only  a 
limited  supply  of  water  is  available  at  a  considerable  depth,  supply- 


10  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

ing  water  to  a  limited  area  per  pump.  They  operate  very  efficiently 
against  any  head  when  new  and  if  moving  clear  water,  but  they  are 
subject  to  excessive  wear  along  the  close-fitting  surfaces  if  the  water 
contains  abrasive  material.  They  require  constant  attention  under 
these  conditions  as  they  soon  cease  to  function  economically  after 
wear  starts.  They  do  not  need  to  be  primed  to  start  pumping  if  they 
are  in  good  condition.  In  fact,  small  plunger  pumps  are  used  as 
priming  units  for  centrifugal  installations. 


AIR-LIFT    PUMPS 

The  air-lift  pump,  as  its  name  implies,  uses  air  to  lift  or  float  the 
water  from  the  source  of  supply.  A  compressor  injects  the  air,  which 
is  sent  to  the  bottom  of  the  pump  through  a  line  of  pipe  let  down 
vertically  into  the  water.  The  pipe  enters  the  bottom  of  the  larger 
pump  pipe  column  (fig.  9) .  The  air  carries  out  with  it  as  it  rises  to  the 
top  of  the  pipe,  a  certain  amount  of  the  water.  For  correct  operation, 
at  least  two-thirds  of  the  length  of  the  pump  must  be  below  the  surface 
of  the  water  supply.  When  the  discharge  is  at  some  point  above  the 
ground  surface,  a  still  greater  portion  must  be  submerged.  Even  with 
the  best  of  conditions,  an  air-lift  pump  has  a  very  low  efficiency.  Its 
application  in  irrigation  is,  therefore,  very  limited.  It  should  find 
increasing  use,  however,  in  the  development  of  wells,  since  there  are 
no  moving  parts  to  be  injured  by  abrasion. 

ROTARY    DISPLACEMENT    PUMPS 

The  rotary  displacement  pump  is  another  device  limited  somewhat 
in  irrigation  use  by  lack  of  capacity.  Though  it  is  made  with  many 
forms  of  internal  design,  all  are  dependent  upon  the  rotary  motion 
of  eccentrically  shaped  or  gear-like  impellers  that  turn  in  the  pump 
case  in  close-running  fit.  Because  of  their  shape,  they  mesh  to  seal 
off  part  of  the  water  in  the  case  at  a  certain  point  in  their  revolution 
and  then,  turning  further  in  mesh,  eject  the  water  into  the  discharge 
pipe  (fig.  1).  As  they  are  capable  of  creating  a  considerable  partial 
vacuum  if  they  are  kept  in  good  condition,  they  do  not  need  to  be 
filled  with  water  to  start  pumping,  provided  they  are  not  too  far  above 
the  supply  source.  They  are  occasionally  used  to  prime  centrifugal 
pumps.  Because  the  action  of  the  pump  depends  upon  the  close  fit  of 
the  impellers,  the  inclusion  of  abrasive  material  in  the  water  being 
moved  is  disastrous  to  their  operation.  They  require  constant  atten- 
tion if  the  water  they  handle  carries  such  material,  this  being  their 


ClRC-312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS 


11 


chief  disadvantage.  They  show  a  good  efficiency  Avhile  the  running 
parts  are  tight  but  drop  off  rapidly  when  wear  starts.  This  type  of 
pump  is  not  applicable  to  deep  well  pumping. 


CURVE    SHEETS 

It  is  the  custom  of  salesmen  in  speaking  of  a  pump  to  refer  to  its 
curve  sheet.  Such  a  sheet  is  very  useful  because  it  gives  a  graphic 
picture  of  the  operation  of  the  pump  in  question.  Figure  4  gives 
curves  for  one  pump  at  the  given  speed  and  the  efficiency  discharge 
curve  of  a  second  at  that  same  speed.  To  use  the  curves  one  proceeds 
in  the  following  manner : 


200  300  400  £00  600  700 

Discharge  in  gat/ons  per  minute 

Fig.  4. — Curve  sheet  for  centrifugal  or  deep  well  turbine  pump;  speed  1165 
r.p.m.  The  solid  lines  refer  to  the  first  pump.  The  dotted  line  is  the  efficiency 
curve  for  the  second  pump,  which  shows  an  undesirable  curve  for  conditions  of 
varying  pumping  heads.  Each  curve  represents  the  relationship  of  two  factors; 
e.g.,  each  of  the  curves  labelled  "Plant  efficiency — Discharge"  represents  the 
relationship  of  the  efficiency  of  one  of  the  plants  to  its  discharge. 

First,  note  that  the  three  solid-line  curves  are  drawn  for  a  pump 
when  turning  at  1165  revolutions  per  minute,  for  which  speed  it  was 
designed  and  at  which  speed  it  operates  best,  If  driven  at  any  other 
speed,  this  pump  will  have  different  sets  of  curves.  Also  note  that 
the  horizontal  base  line  is  scaled  to  read  discharge  in  gallons  per 
minute,  while  the  vertical  line  indicates  pumping  head,  plant  effici- 
ency, and  horsepower  to  motor. 

The  most  important  thing  shown  in  the  plant-efficiency — discharge 
curve  for  the  first  pump  is  that  when  the  highest  point  of  efficiency 


12  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

or  60  per  cent,  is  reached  at  460  gallons  per  minute  discharge  against 
98  feet  pumping  head,  the  input  horsepower  to  the  motor  will  be 
18.5  horsepower.  If  the  head  pumped  against  is  not  at  this  point, 
the  efficiency  is  lower.  The  single  dotted  line  indicates  the  efficiency- 
discharge  curve  of  the  second  pump.  It  illustrates  a.  characteristic 
design,  in  which  a  small  change  in  head  or  discharge  will  create  a  large 
change  in  efficiency,  as  compared  to  the  first  pump  whose  efficiency 
curve  is  not  so  steep.  It  is  evident,  therefore,  that  the  second  pump 
is  less  desirable  than  the  first  where  pumping  lifts  are  likely  to  vary. 
A  prospective  pump  owner,  then,  should  buy  a  pump  having  a  flat- 
topped  efficiency-discharge  curve,  if  his  water  levels  are  liable  to  vary. 
Where  constant  lifts  are  assured,  a  sharp-pointed  efficiency  curve  is 
not  objectionable,  if  the  point  of  maximum  efficiency  fits  the  operating 
conditions.  When  pumping  lifts  are  sure  to  increase,  the  pump  should 
be  purchased  to  operate,  when  first  installed,  at  a  point  to  the  right 
of  the  point  of  maximum  efficiency  rather  than  to  the  left.  The 
operating  conditions  will  then  become  constantly  better  for  a  time 
after  installation. 

THE  SELECTION  OF   MACHINERY 

The  above  description  of  the  different  types  of  irrigation  pumps 
has  indicated  that  each  type  is  adapted  to  some  particular  condition, 
such  as  high  or  low  water  table,  or  large  or  small  discharge.  There 
are,  however,  so  many  makes  of  pumping  plants  available  that  the 
buyer  is  often  at  a  loss  to  determine  which  to  select.  He  should  first 
consider  his  power  unit,  which  will  be  driven  through  a  belt  if  a  fuel- 
oil  engine  is  selected.  Since  pumping  is  a  steady  load  on  an  engine, 
the  latter  must  be  large  enough  to  drive  the  pump.  Unless  over 
capacity  is  allowed,  the  life  of  the  engine  is  materially  shortened. 
This  is  particularly  true  in  the  case  of  light-duty  engines  such  as 
those  coming  from  pleasure  cars.  If  an  electric  drive  is  to  be  used, 
the  buyer  must  determine  whether  it  is  to  be  direct  or  belt  connected. 
Though  both  connections  have  advantages,  the  direct  insures  positive 
speed  maintenance  and  eliminates  some  loss.  The  make  of  pump 
selected  should  depend  upon  the  service  obtainable  from  the  sellers  in 
the  given  area,  provided  that  the  products  of  several  reputable  manu- 
facturers are  represented. 

A  standard  form  of  agreement2  to  cover  the  sale  and  purchase 
of  irrigation  pumping  equipment  has  been  drafted  by  a  committee 


2  Moses,  B.  D.,  and  L.  S.  Wing.    Farmers'  Purchase  agreement  for  deep  well 
pumps.     California  Agr.  Exp.  Sta.  Bui.  448:1-46.     1928. 


CIRC.  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS  13 

representing  the  pump  manufacturers,  the  California  Farm  Bureau 
Federation,  and  other  organizations.  No  buyers  should  fail  to'  see 
that  his  sale  contract  follows  the  standard  form.  Since  this  agree- 
ment is  in  substance  a  guarantee  of  the  performance  of  the  plant 
purchased,  it  affords  protection  to  sellers  and  manufacturers,  as  well 
as  consumers,  throughout  the  state.  Some  satisfactory  form  of  written 
agreement  as  to  performance  should  be  given  with  every  purchase  of 
a  plant. 

WATER    SUPPLIES 

As  was  indicated  earlier  in  this  circular,  there  are  two  sources 
of  water  for  irrigation,  namely,  surface  and  underground  waters. 
Underground  supplies  are  located  in  the  gravels  and  sands  laid  down 
by  the  streams  of  ancient  times.  They  are  supplied  by  percolation 
from  the  rains  and  streams  of  the  present  day,  mainly  the  latter. 
Many  of  these  streams  of  years  ago  sprang  from  the  same  hills  and 
mountains  as  those  of  today.  The  beds  of  the  present  streams, 
therefore,  often  cut  the  old  gravel  and  sand  deposits  on  the  mountain 
sides  and  much  of  the  water  in  the  stream  sinks  into  them,  to  be 
recaptured  only  by  pumping. 

Because  these  gravels  and  sand  strata  are  often  supplied  by  waters 
flowing  at  a  high  elevation,  they  are  sometimes  found  in  the  valley 
floor  under  sufficient  hydraulic  pressure  to  cause  the  water  to  flow  out 
of  the  well.  Most  of  them  are  under  some  hydraulic  pressure,  so  that 
the  water  rises  part  way  up  the  well  casing,  at  least,  when  the  strata 
are  encountered.  Wells  of  this  type  are  called  artesian  wells  whether 
they  flow  or  not.  Since  the  water  travels  slowly  through  these  water 
strata,  irrigation  pumping  often  tends  to  take  the  water  faster  than  it 
can  be  supplied.  The  pressure  in  the  strata  is  thus  reduced  and  the 
pumping  level  lowered.  When  the  draft  is  large,  this  lowering  is 
often  felt  in  every  well  drawing  from  the  same  strata.  Unless  the 
winter  rains  and  the  streams  can  replenish  the  supply  during  slack 
pumping  periods,  the  drop  may  become  permanent.  The  water  table 
may  continue  to  be  lowered  in  heavily  pumped  areas  until  pumping 
becomes  uneconomical. 

The  sinking  of  wells  to  develop  underground  waters  has  led  to  the 
production  of  a  special  class  of  machinery.  A  large  soil  auger  is  used 
to  bore  into  the  earth.  Sometimes  a  scow  or  sand  bucket  is  oscillated 
up  and  down  in  earth  and  water  in  the  hole,  gathering  in  a  certain 
part  of  this  mixture  through  a  flap  valve  located  at  the  bottom.  Heavy 
drills  or  rock  bits  that  pound  their  way  downward  are  used  in  areas 


va/ve 


Cutting    Mn/ves 


a 


D 


f^r> 


,4  Scow  or  Sbnd pump 

3  duger  or  boring  too/ 

C  Pope  sochef 

D  Pope    sockef  sub 

£  Uars  or  /iommers 

F  Scow  or  fbmp  *?ub 

O  Pock  bif 


Fig.  5. — Types  of  well-drilling  tools  used  in  California. 


ClKC.  312J      OPERATION  OF  SMALL  IRRIGATION   PUMPING  PLANTS 


15 


where  rock  or  boulders  are  encountered,  the  loosened  material  being 
brought  to  the  surface  with  a  sand  bucket.  Heavy  drilling  is  further 
aided  by  the  use  of  massive  jars  or  hammers,  which  give  an  additional 
blow  upon  the  bit  or  scow  (fig.  5).    These  tools  are  operated  by  well 


^m 


Fig.  6. — Typical  well  rig  used  for  heavy  drilling.    Note  scow  being  dumped. 

rigs,  consisting  of  a  portable  power  plant  with  a  tower  at  one  end 
(fig.  6),  over  which  a  cable  is  run  for  the  operation  of  the  scow  or 
similar  tools,  and  for  the  withdrawal  of  the  auger-type  tools.  The 
augers  are  actuated  by  a  turn  table,  powered  through  a  chain  or  belt 


16  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

drive  from  the  well  rig.  The  hole  made  by  the  drilling  tool  is  gener- 
ally lined  with  metallic  casing  forced  down  as  rapidly  as  space  is 
provided  for  it  below. 

Casing  is  usually  either  screw-joint  pipe  or  so-called  *  stove-pipe' 
casing.  Both  may  be  obtained  for  almost  any  sized  well.  Stove-pipe 
casing  is  made  from  No.  18  or  thicker  sheet-iron  in  2-foot  sections 
which  are  lapped  over  each  other  for  half  their  lengths  to  form  a  pipe 
whose  surfaces  are  smooth  inside  and  out,  and  whose  walls  are  a 
double  thickness  of  the  sheet  metal  used.  Variations  of  these  two 
types  are  in  use,  but  not  generally  in  California.  One  of  these,  a 
single-riveted  casing,  is  used  to  some  extent  in  the  smaller  wells.  It 
is  made  of  a  single  thickness  of  fairly  light  sheet-iron. 

While  the  well  is  being  drilled,  a  record  must  be  kept  of  the 
position  of  the  water-bearing  strata  encountered,  in  order  that  the 
casing  may  be  perforated  in  these  areas.  Perforating  is  done  by  the 
well  rig,  unless  manufactured  perforated  casing  has  been  obtained 
for  direct  insertion  into  the  well  while  drilling  is  in  progress.  Many 
contrivances  have  been  used  to  perforate  casing,  including  both 
cutting  knives  and  punches,  but  none  have  been  found  entirely  satis- 
factory. Some  wells  are  never  perforated.  These  depend  upon  the 
flow  attainable  from  the  bottom  opening  alone  and  are  called  open- 
bottom  wells.  It  is  only  occasionally,  however,  that  a  sufficient  supply 
can  be  obtained  from  this  opening  alone.  On  the  other  hand,  it  is 
common  to  seal  the  bottoms  of  wells  taking  their  supply  through 
perforations,  making  them  closed-bottom  wells.  The  perforations 
are  slits  or  regular-shaped  holes  in  the  walls  of  the  casing  and  are 
arranged  more  or  less  uniformly  about  the  circumference  of  the  well 
opposite  the  water-bearing  strata.  Unless  sufficient  openings  are  made 
in  the  casing,  the  resistance  to  flow  through  it  will  be  excessive,  and 
the  water  will  be  unduly  lowered,  thereby  increasing  pumping  costs. 

One  special  form  of  well  consists  of  a  hole  large  in  diameter 
and  sunk  with  a  rotating  auger  or  drill,  from  which  water  is 
ejected.  The  water  washes  the  loosened  materials  from  the  well. 
Into  this  hole  a  casing  of  smaller  diameter  is  inserted,  the  outside  of 
which  is  surrounded  with  coarse  clean  gravel.  This  method  is  used 
to  provide  a  greater  area  of  entrance  for  the  ground-waters,  since  the 
whole  casing  may  be  perforated.  The  clean  gravel  cylinder  on  the 
outside  permits  easy  access  to  the  water.  The  drilling  process,  how- 
ever, may  puddle  the  walls  of  the  well,  thus  defeating  the  purpose 
somewhat.  In  some  localities  where  the  materials  penetrated  are 
self-supporting,  wells  may  not  require  casing. 


CIRC.  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS  17 

Almost  all  wells  when  first  completed  require  developing.  That 
is,  they  must  be  pumped  for  a  considerable  time  to  draw  the  fine 
particles  of  earth  away  from  the  water  strata  into  the  well  and  out 
through  the  discharged  stream.  After  the  fine  particles  have  been 
removed  from  the  water  strata,  the  flow  usually  increases,  because  the 
water  can  pass  through  the  strata  more  readily.  The  discharged  water 
also  becomes  clear.  As  has  been  previously  suggested,  the  air-lift  can 
be  used  very  satisfactorily  for  developing  wells  because  it  has  no 
moving  parts.  Deep  wells  should  be  developed  before  the  pumping 
equipment  is  ordered.  Such  a  practice  would  greatly  lengthen  the 
life  of  the  equipment.  The  pumps  would  then  operate  at  higher 
efficiencies,  since  they  could  be  purchased  to  meet  known  conditions 
of  operation,  and  would  not  be  subjected  to  the  abrasion  incident  to 
the  development  of  the  wells. 


WELL   AND   PUMP  TESTS 

After  a  well  has  been  developed,  it  should  be  tested  to  determine 
the  depth  to  water  when  the  desired  discharge  stream  is  being 
obtained.  This  is  important  because  these  measurements  indicate  the 
character  of  the  well.  If  possible,  the  test  pump  should  be  run  at 
several  different  speeds,  readings  of  discharge  and  depth  to  water 
being  obtained  for  the  well  while  the  pump  is  operating  at  each  speed. 
In  this  way,  the  actual  tendency  of  the  well  can  be  determined  and 
the  pumping  lift  for  any  discharge  can  be  estimated.  This  type  of 
data  is  plotted  as  a  curve  (fig.  7)  enabling  one  to  know  fairly  accur- 
ately what  the  probable  conditions  of  operation  will  be  beyond  the 
range  of  the  observed  data. 

The  curve  in  figure  7  is  typical  of  nearly  all  wells  in  California. 
That  is,  the  water  stands  in  the  well  at  a  certain  depth ;  when  pumping 
is  in  progress,  this  depth  increases  as  the  amount  being  discharged 
increases.  The  amount  of  change  in  depth,  or  draw-down,  with 
changing  discharge  is  not  the  same  for  all  wells,  but  depends  upon 
the  ease  with  which  the  water  passes  through  the  water-bearing  strata 
and  the  well  perforations.  The  more  easily  the  water  moves  into  the 
well,  the  smaller  will  be  the  change  in  water  level  for  any  given 
discharge  rate.  The  guesswork  usually  practiced  for  determining 
these  data  cannot  possibly  fit  a  pump  to  a  given  well  accurately. 

It  is  as  important  to  test  the  new  pumping  plant  when  it  is  in 
place  as  it  is  the  developed  well.  Since  there  is  always  a  chance  for 
a  slip  in  the  installation  of  machinery  of  any  type,  it  is  to  the  advant- 


18 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


age  of  the  owner,  seller,  and  power  company  to  test  every  new  pump 
installed.  Such  a  test  should  cover  the  following  items:  discharge, 
pumping  lift,  power  requirement,  and,  of  general  interest  but  not 
entirely  necessary,  the  speed  of  rotation  of  the  pump  and  motor. 

Discharge  may  be  obtained  as  follows:  Allow  the  discharge  from 
the  pump  to  fall  into  an  open  ditch,  across  which  has  been  constructed 
a  bulkhead  with  a  weir  notch,  similar  to  that  shown  in  figure  8. 
Make  sure  that  the  ditch  is  large  enough  so  that  the  water  may 
approach  the  weir  without  undue  haste  or  turbulence.    Be  sure  that 


so 

46 

( 

7/?or 

-acte 

risli 

s  C 

jrve 

'  of 

a  ft 

'ell 

46 

\M 

^4a 

%3S 

§36 

t 

o 

c 

30 

as 

£6 

<£W 


£50 


30O  350  400  450  500 

Discharge  in  Oollons  per  Minute 


550 


600 


Fig.  7. — Curve  resulting  from  plotting  well-test  data. 


the  weir  crest  is  horizontal  and  the  bulkhead  perpendicular  to  the 
ground.  Place  a  small  stake  a  few  feet  back  from  the  weir  and 
beside  one  bank  of  the  ditch,  with  its  top  just  level  with  the  crest  of 
the  wreir,  as  shown  in  figure  8.  A  carpenter's  level  may  be  used  to 
set  the  stake  correctly  in  relation  to  the  weir  crest.  A  ruler  held 
perpendicularly  with  the  zero  end  resting  on  the  top  of  the  stake  will 
indicate  the  depth  of  water  flowing  over  the  weir.  The  discharge  may 
be  determined  by  inspection  of  the  accompanying  weir  table  (table  1). 
The  flow  in  gallons  per  minute  for  weirs  of  different  widths  is 
indicated  opposite  the  readings  of  head  in  inches,  as  measured  on  the 
stake  in  the  wier  pond.  The  flow  found  in  the  table  corresponding  to 
the  measured  head  for  the  weir  used  is  the  discharge  for  the  pump. 


CIRC.  312]      OPERATION  OF  SMALL  IRRIGATION   PUMPING  PLANTS 


19 


The  method  of  measuring  the  pumping  lift  varies  somewhat  with 
different  types  of  pumps,  on  account  of  the  different  uses  and  mount- 
ings. In  the  case  of  such  pumps  as  the  centrifugal,  whose  suction  and 
discharge  lines  are  completely  accessible,  the  following  methods  of 
measurements  are  followed.  A  vacuum  gage  is  mounted  on  the  suction 
pipe  as  near  the  pump  as  possible ;  if  the  discharge  line  extends  to 
some  distance  from  the  pump,  a  pressure  gage  is  tapped  into  it  also, 


%W^  bulkhead  set 
\\\:^Kjnto  d/'fch  bank 


Beye/ed  edge  of 
yve/r  up  stream 


Fig. 


top  or~  stoke  /eve/ with    ""^ 
cr&st  of  weir 

8. — Rectangular  weir  in  place.     A   indicates  necessary  clearance  of 
five  or  more  inches  between  edges  of  weir  and  ditch  banks. 


close  to  the  pump.  The  sum  of  the  readings  of  these  two  gages  con- 
verted into  feet,  plus  the  vertical  distance  between  the  centers  of  the 
gages,  gives  the  pumping  lift.  If  the  water  is  discharged  from  the 
pump  close  at  hand,  the  pumping  lift  becomes  suction-gage  reading  in 
.feet,  plus  the  vertical  distance  from  the  suction-gage  center  to  the 
center  of  the  discharge  pipe  at  its  highest  point. 

In  the  case  of  pumps  whose  suction  and  discharge  lines  are  inacces- 
sible, the  pumping  lift  may  be  calculated  roughly  from  pipe-friction 
tables,   adding  the  measured  vertical  distance  between  the   highest 


TABLE   1 

Discarge  Table  for  Eectangular  Weirs 


Head 

Discharge 

in  gallons 

per  minute  for  crests  of  various 

lengths 

inches 

lfoot 

1.5  feet 

2  feet 

3  feet 

4feet 

2% 

131 

197 

264 

399 

534 

2H 

140 

212 

284 

428 

575 

2M 
2% 

2V% 

150 

227 

304 

458 

615 

161 

242 

325 

489 

655 

171 

258 

345 

521 

696 

3 

181 

273 

367 

552 

741 

$ 

192 

290 

388 

588 

785 

203 

306 

410 

619 

830 

3^ 

214 

323 

433 

655 

875 

VA 

225 

340 

458 

687 

920 

&A 

237 

357 

480 

723 

969 

m 

248 

375 

503 

759 

1,014 

3»fl« 

260 

393 

530 

794 

1,064 

3^16 

272 

411 

552 

835 

1,113 

4tf6 

285 

430 

575 

871 

1,167 

4?ie 

297 

448 

601 

907 

1,216 

4#6 

309 

467 

628 

947 

1,266 

4?16 

322 

485 

651 

987 

1,320 

4%6 

334 

507 

678 

1,023 

1,373 

4Hie 

347 

525 

705 

1,064 

1,427 

4^6 

361 

543 

731 

1,104 

1,481 

4^16 

374 

566 

759 

1,145 

1,534 

5Vi6 

387 

583 

785 

1,189 

1,589 

5?'l6 

401 

606 

812 

1,230 

1,647 

5M 

415 

628 

844 

1,270 

1,706 

5^ 

429 

646 

871 

1,315 

1,764 

5}^ 

443 

669 

898 

1,360 

1,818 

5% 

458 

691 

929 

1,400 

1,876 

5% 

471 

714 

956 

1,445 

1,939 

5Vs 

485 

736 

987 

1,490 

1,997 

6 

498 

754 

1,014 

1,534 

2,056 

6H 

516 

776 

1,046 

1,580 

2,118 

m 

530 

799 

1,077 

1,625 

2,181 

&A 

543 

826 

1,104 

1,674 

2,240 

VA 

561 

848 

1,136 

1,719 

2,303 

m 

575 

871 

1,167 

1,768 

2,365 

QH 

588 

893 

1,198 

1,813 

2,433 

m» 

606 

916 

1,230 

1,863 

2,494 

6»%6 

619 

938 

1,261 

1,912 

2,558 

7H« 

637 

965 

1,293 

1,957 

2,626 

7?'l6 

651 

987 

1,329 

2,006 

2,693 

7%6 

669 

1,010 

1,360 

2,060 

2,756 

77/l6 

682 

1,037 

1,391 

2,105 

2,823 

7?i6 

700 

1,059 

1,423 

2,159 

2,890 

7Hie 

718 

1,086 

1,459 

2,208 

2,958 

71?i6 

732 

1,109 

1,490 

2,258 

3,030 

7»%6 

750 

1,136 

1,526 

2,311 

3,097 

m» 

768 

1,162 

1,557 

2,361 

3,164 

8?i6 

781 

1,185 

1,598 

2,415 

3,236 

8Ji 

799 

1,212 

1,629 

2,464 

3,303 

8^ 

817 

1,239 

1,665 

2,518 

3,375 

8K2 

835 

1,261 

1,697 

2,572 

3,447 

SVs 

853 

1,288 

1,732 

2,626 

3,519 

m 

866 

1,315 

1,768 

2,680 

3,591 

w 

884 

1,342 

1,804 

2,733 

3,667 

9 

902 

1,369 

1,840 

2,787 

3,739 

9M 

920 

1,396 

1,876 

2,841 

3,811 

m 

938 

1,423 

1,912 

2,895 

3,887 

Ws 

956 

1,450 

1,948 

2,953 

3,959 

m 

974 

1,477 

1,984 

3,007 

4,035 

m 

992 

1,504 

2,024 

3,066 

4,111 

m 

1,010 

1,531 

2,060 

3,119 

4,188 

mu 

1,028 

1,557 

2,096 

3,178 

4,264 

9»%a 

1,046 

1,589 

2,132 

3,236 

4,340 

10V.6 

1,064 

1,616 

2,172 

3,290 

4,416 

10^16 

1,082 

1,643 

2,208 

3,348 

4,493 

10%6 

1,104 

1,670 

2,249 

3,407 

4,574 

ioy,6 

1,122 

1,701 

2,289 

3,465 

4,650 

lOfiti 

1,140 

1,728 

2,325 

3,523 

4,731 

ioiy.6 

1,158 

1,759 

2,365 

3,586 

4,807 

101?'l6 

1,176 

1,786 

2,401 

3,645 

4,888 

io'y16 

1,198 

1,818 

2,442 

3,703 

4,969 

lHie 

1,216 

1,845 

2,482 

3,761 

5,049 

119ia 

1,234 

1,876 

2,522 

3,824 

5,130 

nx 

1,252 

1,903 

2,563 

3,882 

5,211 

n*A 

1,275 

1,934 

2,603 

3,945 

5,292 

nlA 

1,293 

1,961 

2,644 

4,008 

5,377 

n% 

1,315 

1,993 

2,684 

4,066 

5,458 

u% 

1,333 

2,024 

2,724 

4,129 

5,539 

WA 

1,351 

2,051 

2,760 

4,192 

5,624 

12 

1,373 

2,083 

2,805 

4,255 

5,709 

CIRC.  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS  21 

point  of  discharge  and  the  supply  water  surface.  Such  figures  are 
useful  only  for  making  a  rough  check  of  the  operation  of  a  pumping 
plant. 

For  pumps  such  as  the  deep  well  turbines  installed  in  such  a  way 
that  their  suction  lines  are  inaccessible,  but  whose  discharge  lines  may 
be  tapped,  measurement  is  made  of  the  distance  in  feet  from  the  ground 
surface  to  the  surface  of  the  supply  water.  To  this  is  added  the  vertical 
distance  from  the  ground  surface  to  the  center  of  the  discharge  pipe  at 
its  highest  point,  if  the  discharge  is  close  to  the  pump.  If  it  is  not,  a 
pressure  gage  must  be  tapped  into  the  discharge  line  and  its  reading 
in  feet  must  be  added  to  the  vertical  distance  in  feet  between  the 
center  of  the  gage  and  the  ground  surface,  plus  the  vertical  distance 
in  feet  between  the  ground  surface  and  the  supply- water  surface. 
Manufacturers  of  deep  wTell  turbines  consider  the  part  of  the  dis- 
charge column  pipe  below  ground  as  a  portion  of  the  pump,  making 
the  pumping-lift  readings  as  obtained  above  acceptable. 

The  measurement  of  the  vertical  distance  between  the  ground  and 
water-supply  surface  may  be  obtained  only  through  the  use  of  a 
sounding  line  (fig.  9).  This  may  be  an  electrically  insulated  wire 
with  an  exposed  end  let  down  into  the  well  so  that  it  will  ground  in 
the  water,  making  a  complete  circuit  with  a  bell  ringer  in  it.  Measure- 
ment of  the  length  of  line  will  give  the  depth  to  water.  On  the  other 
hand,  it  may  be  an  air  line  of  pipe  of  known  length  run  down  into 
the  well  with  the  pump.  Air  is  forced  into  this  line  and  the  maximum 
pressure  obtainable  is  recorded  in  pounds  or  feet  on  a  gage  at  the  sur- 
face (fig.  9).  Some  of  these  gages  read  the  number  of  feet  to  water 
direct.  Those  reading  in  pounds  must  be  corrected  to  feet  by  multi- 
plying the  reading  by  2.31  (1  pound  equals  2.31  cubic  feet  of  water). 
This  number  of  feet  indicates  the  submersion  of  the  end  of  the  air 
line.  Subtracting  the  submersion  in  feet  from  the  total  length  of  the 
line  in  feet  gives  the  distance  to  water.  Example :  A  120-foot  air  line 
in  a  well  being  pumped  requires  13  pounds  air  pressure  to  force  the 
water  out  of  the  line.  The  pressure  goes  no  higher  than  13  pounds, 
because  the  air  escapes  at  the  bottom  as  fast  as  more  is  added  when 
this  point  is  reached.  Thirteen  pounds  equals  13  X  2.31  feet  of  water 
or  30.03  feet  of  water  (call  it  30  feet),  the  submersion  of  the  end  of 
the  air  line.  Therefore,  the  depth  to  water  is  120  feet  less  30  feet,  or 
90  feet.  A  direct  reading  pressure  gage  scaled  in  feet  would  have 
indicated  90  feet  immediately  under  these  conditions.  All  pump 
installations  should  be  designed  to  permit  measurements  of  the  depth 
of  water.  Special  precautions  must  be  taken  to  make  this  possible  in 
placing  deep  well  pumps. 


Ground  wire 
to  purnpy 


Telephone 
mogneto 


Air  sounding 
line  @" pipe) 


Pumping 
yvoter  /'eye I 

L 

"Sore  end 
on  //he 


ferfbrvted 
**  cosing 


Fig.  9. — Diagram 
of  air-lift  pump  in 
well,  showing  two 
methods  of  sound- 
ing depths  in  wells. 


\4/r  iine  from  compressor 
enters  pump   column 
of  bottom. 


ClEG.  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS 


23 


The  power  input  may  be  measured  readily  in  the  field  only  for 
electrically  driven  units.  Although  the  power  companies  will  be  glad 
to  assist  in  this  measurement,  the  owner  can  determine  it  for  himself 
after  ascertaining  the  number  of  watts  registered  by  the  electric  meter 
in  his  pumping  plant  for  each  revolution  of  the  aluminum  disk 
(fig.  10).  He  should  be  sure  that  the  figure  furnished  in  watts 
includes  any  special  set-up  constants  for  the  installation.     After  this 


WATT     HOUR    METER 


'Count  rero/L/f/ons 
of  f/v's  cf/^k 

Fig.  10. — Electric-meter  indicating  disk.     In  making  a  pumping-plant 
test,  the  revolutions  of  this  disk  are  to  be  counted. 

figure,  commonly  known  as  a  disk  constant,  is  obtained,  the  number 
of  revolutions  of  the  aluminum  disk  should  be  counted  for  several 
minutes  and  the  total  divided  by  the  exact  number  of  minutes  counted. 
This  figure  should  be  multiplied  by  the  constant  obtained  from  the 
power  company,  and  the  result  multiplied  by  60  and  divided  by  746. 
The  final  figure  is  the  horsepower  being  supplied  to  the  motor.  With 
the  completion  of  this  step,  the  over-all,  or  plant  efficiency,  may  be 
computed  as  follows :  Multiply  the  discharge  in  gallons  per  minute  by 


24  UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION 

the  weight  of  a  gallon  of  water  (8.33  pounds)  and  multiply  this  by 
the  distance  the  water  is  lifted,  in  feet.  Then  divide  the  result  by 
33,000.     The  result  is  horsepower  represented  by  water  pumped. 

The  plant  efficiency  is  the  important  item  to  the  user,  since  it  tells 
how  well  the  whole  unit  is  working.  From  the  buyer's  viewpoint  the 
seller  should  specify  the  plant  efficiency  when  indicating  the  char- 
acteristic of  operation.  The  over-all  or  plant  efficiency  is  the  water 
horsepower  output  divided  by  the  electrical  horsepower  input,  with 
the  result  multiplied  by  100.  Checking  the  speed  of  an  electrically 
driven  unit  will  occasionally  demonstrate  a  faulty  motor,  but  this 
condition  is  seldom  found.  Plants  not  electrically  driven  may  be 
tested  to  determine  the  discharge,  the  head  pumped  against,  and  the 
speed  of  rotation.  The  last  named  requires  the  use  of  a  speed  counter, 
which  most  pump-installation  men  have  in  their  equipment.  If  the 
pump  is  up  to  the  speed  specified,  it  should  deliver  the  quantity  of 
water  indicated  by  the  seller  for  the  head  being  pumped  against. 

Tests  of  an  irrigation  pumping  plant  should  be  made  occasionally 
throughout  its  life  so  that  the  necessary  adjustments  may  be  made 
to  maintain  a  satisfactory  efficiency. 


DISCUSSION    OF    FIELD    CONDITIONS 

Operators  of  irrigation  pumping  equipment  have  always  felt 
somewhat  dissatisfied  with  the  cost  of  operation  and  the  performance 
of  their  pumping  equipment.  In  order  to  determine  the  sources  of 
this  dissatisfaction,  investigations  were  conducted  in  the  field  during 
parts  of  1924,  1925,  and  1926.  These  consisted  of  field  tests  of  many 
pumping  plants,  conducted  in  as  thorough  a  manner  as  possible.  All 
measurements  were  checked  by  several  readings,  which  were  averaged. 
All  gages  were  checked  for  accuracy  and  in  several  instances  electric 
watt-hour  meters  were  tested  by  the  power  companies  to  make  certain 
of  their  accuracy.  These  instruments  were  seldom  found  more  than 
1  per  cent  in  error  by  the  company  tester.  Wherever  possible,  weirs 
were  used  in  making  readings  of  discharge  and  when  their  use  was 
impossible,  every  effort  was  made  to  insure  accuracy  by  checking 
several  methods  against  each  other.  Soundings  to  water  in  the  wells 
were  made,  where  possible,  with  an  insulated  wire  which  completed 
an  electric  circuit  with  a  bell  ringer  in  it  when  contact  was  made 
with  the  water.  Occasionally,  an  air  line  of  known  length  was  avail- 
able and  sounding  was  made  with  it,  checking  with  the  electric 
sounder  wherever  this  could  be  done.     Tables  2  and  3  indicate  in 


CIRC,  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS 


25 


general  the  results  of  these  tests,  showing  the  average  operating  con- 
ditions for  the  three  types  of  pumps  tested.  These  figures  might  vary 
a  few  points  either  way,  were  they  for  another  set  of  pumping  plants, 
but  they  represent  a  fair  cross-section  of  the  irrigation  pumping 
plants  supplied  by  wells.  They  are  probably  typical  of  the  whole 
state,  since  they  were  taken  in  a  number  of  areas. 

TABLE  2 

Eesults  of  Field  Tests  of  Irrigation  Pumping  Plants 


Type 

Average 
head 

Average 
discharge 

Plant 
efficiency 

Plants 
tested 

Centrifugal 

Deep  well  turbine 

feet 

49.9 
124.0 
81.6 

gals,  per  minute 

3,685.5 

958.5 

1,066.5 

per  cent 

49.8 
40.5 
44.5 

33 
31 

27 

TABLE  3 

Approximate  Characteristics  of  Air  Lift,  Plunger,  and  Eotary 
Displacement  Pumps 


Type 

Average 
discharge 

Average 
efficiency 

Air  lift 

gallons  per  minute 

225 

382.5 

225 

per  cent 
23 

60 

Rotary  displacement 

50-60 

It  will  be  noted  in  the  tables  above  that  the  average  discharge  of 
the  centrifugals  is  considerably  higher  than  for  the  other  two  types 
tested.  This  is  due  to  the  inclusion  of  several  10  and  20-second-foot 
units  among  the  centrifugal-pump  tests.  These  plants  were  about 
twenty  years  old,  and  their  efficiencies  were  still  considerably  above 
the  average  for  the  type.  They  were  much  older  than  any  of  the 
screw  pumps  or  deep  well  turbines  tested.  The  centrifugal  pumps 
of  capacity  corresponding  to  the  other  two  types  showed  about  the 
average  efficiency  of  their  type.  In  many  cases  the  small  centrifugals 
fell  considerably  below  the  average  for  the  type.  Plant  efficiencies 
for  the  three  types  ranged  from  15.2  per  cent  in  several  cases  to  70 
per  cent  in  one  case. 

The  discouraging  feature  of  the  tests  was  that  so  many  plants 
should  be  operating  at  one-half  or  less  than  one-half  of  the  average 
efficiencies  for  the  type.     It  is  apparent  that  the  average  efficiencies 


26  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  11. — Typical  deep-well  pumping  plant  in  house. 


CIRC.  312]      OPERATION  OF  SMALL  IRRIGATION  PUMPING  PLANTS  27 

are  not  ideal,  since  they  represent  conditions  of  power  waste  amount- 
ing to  over  one-half  that  furnished.  Were  the  lowest  efficiencies  up 
to  the  average  for  that  particular  type,  the  owner's  power  bill  would, 
in  some  cases,  be  less  than  half  what  it  is.  Such  conditions  are  largely 
chargeable  to  failure  on  the  part  of  the  owner  to  keep  his  equipment 
in  good  running  order.  There  is  little  excuse  for  centrifugals  to  go 
far  below  their  normal  efficiency  because  they  are  accessible  at  all  times 
and  repairs  are  simple.  The  other  two  types,  as  has  been  mentioned, 
are  more  difficult  to  inspect  and  to  repair.  However,  efficiencies  as 
low  as  some  of  those  found  indicate  that  occasional  tests  will  pay  for 
themselves  by  calling  forth  the  necessary  repairs. 

The  burden  of  fault  does  not  rest  entirely  upon  the  owners  of 
these  plants  showing  low  efficiencies,  because  the  manufacturing  and 
sales  agencies  have  been  responsible  for  some  of  this  trouble.  Their 
equipment  has  not  always  stood  up  in  service  as  it  should,  because 
makeshifts  in  construction  have  been  employed.  Part  of  these  make- 
shifts are  the  result  of  efforts  on  the  part  of  manufacturers  to  attain 
a  low  sale  price  for  their  products  in  order  to  meet  competition. 
Such  practice  is  not  countenanced  by  the  more  reputable  manufac- 
turers, but  the  individual  buyers  of  pumping  equipment  often  mistake 
poorly  made  machines  for  bargains.  The  electric  motor  or  the  electric 
distribution  system  may  be  responsible  for  low  efficiencies  of  operation 
in  pumping  plants,  but  this  is  the  exception  rather  than  the  rule. 
When  an  operator  has  become  suspicious  of  his  electrical  equipment, 
he  should  first  make  sure  that  the  fault  is  not  in  the  pump. 


SUMMARY 

Centrifugal  pumps  are  simple  and  are  easily  cared  for.  They  are 
located  on  ground-surface  foundations  or  in  open  pits,  as  a  rule.  They 
are  best  fitted  to  operate  where  the  water  supply  is  readily  approach- 
able, as  in  the  case  of  surface  waters  or  shallow  underground  supplies. 
When  correctly  installed,  their  efficiency  should  be  good. 

Deep  well  turbine  pumps  are  much  like  the  centrifugals  in  per- 
formance, but  they  are  not  so  easily  inspected  and  kept  in  repair. 
They  may  be  used  to  pump  water  from  almost  any  depth,  and  if 
inspected  and  repaired  occasionally,  should  show  good  operating 
efficiency. 

Screw-type  pumps  lend  themselves  to  a  variety  of  applications 
including  both  long  and  short  lifts.  Its  characteristic  is  its  large 
capacity.     In  the  deep  well  units,  it  is  hampered  in  its  performance 


28  UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION 

by  the  fact  that  it  is  not  easily  inspected.  Its  efficiency  is  good  if  it 
is  inspected  and  repaired  occasionally. 

The  air-lift  pump  has  as  its  chief  asset  its  simplicity  and  lack  of 
wearing-  parts,  thus  making  it  suitable  for  use  in  developing  wells. 
Its  application  to  irrigation  is  limited  to  special  conditions  because 
of  its  low  efficiency. 

Because  they  are  limited  in  capacity,  the  plunger  pumps  are 
used  generally  in  irrigating  comparatively  small  tracts.  There  are 
many  areas  with  deep  water  supplies  of  limited  capacity  served 
largely  by  this  type  of  pump.  Plunger  pumps  are  also  limited  in 
use  by  the  fact  that  abrasive  materials  in  the  water  supply  soon  cut 
them  out,  destroying  their  otherwise  very  good  efficiency. 

The  rotary  displacement  pump  is  very  similar  to  the  plunger 
pump  in  its  application  to  irrigation.  It  has  the  same  limitations  as 
the  latter  and  also  it  can  be  used  only  where  there  are  surface  or 
shallow  underground  waters. 

To  be  satisfactory,  plant  efficiencies  should  not  be  below  50  per 
cent.  A  large  number  of  plants  in  the  field  operate  considerably 
below  this  figure.  Many  are  doing  so  because  their  owners  or  operators 
have  failed  to  inspect  and  repair  them  as  they  should.  Some  pumps 
are  so  poorly  made  that  they  cannot  maintain  nor  even  attain  50  per 
cent  plant  efficiency.  These  units  may  be  eliminated  through  proper 
selection  by  the  bivyers. 

New  plants  should  be  placed  only  in  a  developed  well  and  should 
be  tested  for  operating  efficiency.  Check  tests  should  be  made 
throughout  the  life  of  all  plants. 


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BULLETINS 


No. 

253.  Irrigation  and  Soil  Conditions  in  the 
Sierra   Nevada   Foothills,   California. 

262.  Citrus  Diseases  of   Florida   and   Cuba 

Compared   with    those   of   California. 

263.  Size  Grades  for  Ripe  Olives. 

268.   Growing  and  Grafting  Olive  Seedlings. 

273.  Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain,  Fresno 
County,   California. 

276.  The  Pomegranate. 

277.  Sudan   Grass. 

278.  Grain    Sorghums. 

279.  Irrigation   of  Rice  in   California. 
283.  The  Olive  Insects  of  California. 
294.  Bean   Culture  in   California. 

304.  A  Study  of  the  Effects  of  Freezes  on 

Citrus    in    California. 
810.   Plum    Pollination. 
312.   Mariout   Barley. 
813.   Pruning      Young      Deciduous      Fruit 

Trees. 
819.  Caprifigs    and   Caprification. 

324.  Storage  of  Perishable  Fruit  at  Freez 

ing  Temperatures. 

325.  Rice     Irrigation     Measurements     and 

Experiments    in    Sacramento   Valley, 

1914-1919. 
328.  Prune   Growing  in    California. 
331.  Phylloxera-Resistant    Stocks. 
835.   Cocoanut   Meal    as    a    Feed    for    Dairy 

Cows   and   Other   Livestock. 
339.  The    Relative    Cost    of    Making    Logs 

from   Small  and  Large  Timber. 
840.  Control     of     the     Pocket     Gopher     in 

California. 

343.  Cheese    Pests    and    Their    Control. 

344.  Cold   Storage   as   an   Aid   to   the   Mar- 

keting of  Plums. 

346.  Almond    Pollination. 

347.  The  Control  of  Red  Spiders  in  Decid 

uous  Orchards. 

348.  Pruning  Young  Olive  Trees. 

349.  A    Study    of    Sidedraft    and    Tractor 

Hitches. 

350.  Agriculture      in      Cut-over      Redwood 

Lands. 

353.  Bovine   Infectious   Abortion. 

354.  Results  of  Rice  Experiments  in    1922. 

357.  A     Self-mixing    Dusting    Machine    for 

Applying      Dry      Insecticides      and 
Fungicides. 

358.  Black    Measles,    Water    Berries,     and 

Related  Vine  Troubles. 

361.  Preliminary    Yield    Tables    for    Second 

Growth   Redwood. 

362.  Dust  and  the  Tractor   Engine. 

363.  The  Pruning  of  Citrus  Trees  in  Cali- 

fornia. 

364.  Fungicidal    Dusts    for    the    Control    of 

Bunt. 

365.  Avocado  Culture  in  California. 

366.  Turkish  Tobacco  Culture,   Curing  and 

Marketing. 

367.  Methods  of  Harvesting  and  Irrigation 

in   Relation  of  Mouldy  Walnuts. 

368.  Bacterial  Decomposition  of  Olives  dur- 

ing Pickling. 

369.  Comparison     of     Woods     for     Butter 

Boxes. 

370.  Browning  of  Yellow  Newtown  Apples. 

371.  The   Relative    Cost   of    Yarding    Small 

and   Large  Timber. 

373.  Pear   Pollination. 

374.  A  Survey  of  Orchard  Practices  in  the 

Citrus    Industry  of    Southern     Cali- 
fornia. 

375.  Results   of   Rice   Experiments   at   Cor- 

tena,    1923. 

376.  Sun-Drying  and  Dehydration  of  Wal 

nuts. 

377.  The   Cold    Storage   of   Pears. 
379.  Walnut   Culture   in   California. 


No. 
380. 

382. 

385. 
386. 

387. 
388. 

389. 
390. 

391. 

392. 
393. 
394. 

395. 
396. 

397. 

398. 
399. 


400. 
401. 

402. 
404. 
405. 
406. 
407. 


408. 
409. 


410. 
411. 
412. 

414. 

415. 
416. 

417. 

418. 

419. 

420. 

421. 
422. 

423. 

424. 

425. 
426. 

427. 

428. 

429. 


Growth  of  Eucalyptus  in  California 
Plantations. 

Pumping  for  Drainage  in  the  San 
Joaquin   Valley,    California. 

Pollination    of   the    Sweet   Cherry. 

Pruning  Bearing  Deciduous  Fruit 
Trees. 

Fig  Smut. 

The  Principles  and  Practice  of  Sun- 
drying  Fruit. 

Berseem  or   Egyptian   Clover. 

Harvesting  and  Packing  Grapes  in 
California. 

Machines  for  Coating  Seed  Wheat  with 
Copper   Carbonate   Dust. 

Fruit    Juice    Concentrates. 

Crop  Sequences  at  Davis. 

Cereal  Hay  Production  in  California. 
Feeding  Trials  with  Cereal  Hay. 

Bark   Diseases  of  Citrus  Trees. 

The  Mat  Bean  (Phaseolus  aeon  it  if  o 
lius). 

Manufacture  of  Roquefort  Type  Cheese 
from    Goat's   Milk. 

Orchard  Heating  in  California. 

The  Blackberry  Mite,  the  Cause  of 
Redberry  Disease  of  the  Himalaya 
Blackberry,    and   its   Control. 

The  Utilization  of  Surplus  Plums. 

Cost  of  Work  Horses  on  California 
Farms. 

The  Codling  Moth  in  Walnuts. 

The  Dehydration  of  Prunes. 

Citrus  Culture  in  Central  California. 

Stationary  Spray  Plants  in  California. 

Yield,  Stand  and  Volume  Tables  for 
White  Fir  in  the  California  Pine 
Region. 

Alternaria  Rot  of  Lemons. 

The  Digestibility  of  Certain  Fruit  By- 
products as  Determined  for  Rumi- 
nants. 

Factors  Affecting  the  Quality  of  Fresh 
Asparagus  after  it  is  Harvested. 

Paradichlorobenzene  as  a  Soil  Fumi- 
gant. 

A  Study  of  the  Relative  Values  of  Cer- 
tain Root  Crops  and  Salmon  Oil  as 
Sources  of  Vitamin  A  for  Poultry. 

Planting  and  Thinning  Distances  for 
Deciduous  Fruit  Trees. 

The  Tractor  on  California  Farms. 

Culture  of  the  Oriental  Persimmon 
in    California. 

Poultry  Feeding:  Principles  and 
Practice. 

A  Study  of  Various  Rations  for 
Finishing  Range  Calves  as  Baby 
Beeves. 

Economic  Aspects  of  the  Cantaloupe 
Industry. 

Rice  and  Rice  By-products  as  Feeds 
for   Fattening   Swine. 

Beef   Cattle   Feeding  Trials,    1921-24. 

Cost  of  Producing  Almonds  in  Cali- 
fornia ;  a  Progress  Report. 

Apricots  (Series  on  California  Crops 
and  Prices). 

The  Relation  of  Rate  of  Maturity  to 
Egg  Production. 

Apple   Growing   in   California. 

Apple  Pollination  Studies  in  Cali- 
fornia. 

The  Value  of  Orange  Pulp  for  Milk 
Production. 

The  Relation  of  Maturity  of  Cali- 
fornia Plums  to  Shipping  and 
Dessert   Quality. 

Economic  Status  of  the  Grape  Industry. 


No. 
87. 
117. 

127. 
129. 
136. 

144. 

157. 
164. 
166. 
170. 

173. 

178. 
179. 

202. 

203. 
209. 
212. 
215. 
217. 

230. 

231. 
232. 

234. 

238. 
239. 

240. 

241. 

243. 

244. 
245. 
248. 

249. 
250. 

252. 
253. 
254. 

255. 

256. 
257. 
258. 


Alfalfa. 

The    Selection    and    Cost    of    a    Small 

Pumping  Plant. 
House   Fumigation. 
The  Control  of  Citrus  Insects. 
Melilotus    indica    as    a    Green-Manure 

Crop  for  California. 
Oidium    or    Powdery    Mildew    of    the 

Vine. 
Control  of  the  Pear  Scab. 
Small  Fruit  Culture  in  California. 
The  County  Farm  Bureau. 
Fertilizing    California     Soils    for    the 

1918  Crop. 
The    Construction    of    the   Wood-Hoop 

Silo. 
The  Packing  of  Apples  in   California. 
Factors   of    Importance   in    Producing 

Milk  of  Low  Bacterial  Count. 
County   Organizations  for   Rural   Fire 

Control. 
Peat   as   a  Manure   Substitute. 
The  Function  of  the  Farm  Bureau. 
Salvaging    Rain-Damaged    Prunes. 
Feeding  Dairy  Cows  in  California. 
Methods   for  Marketing  Vegetables   in 

California. 
Testing  Milk,   Cream,   and   Skim   Milk 

for  Butterfat. 
The   Home   Vineyard. 
Harvesting    and    Handling    California 

Cherries   for   Eastern    Shipment. 
Winter  Injury  to  Young  Walnut  Trees 

during  1921-22. 
The  Apricot  in  California. 
Harvesting     and     Handling     Apricots 

and  Plums  for  Eastern  Shipment. 
Harvesting   and    Handling    Pears    for 

Eastern   Shipment. 
Harvesting  and  Handling  Peaches  for 

Eastern   Shipment. 
Marmalade  Juice  and  Jelly  Juice  from 

Citrus  Fruits. 
Central  Wire  Bracing  for  Fruit  Trees. 
Vine  Pruning  Systems. 
Some   Common    Errors   in   Vine  Prun- 
ing and  Their  Remedies. 
Replacing    Missing    Vines. 
Measurement   of   Irrigation   Water   on 

the  Farm. 
Supports  for  Vines. 
Vineyard  Plans. 
The  Use  of  Artificial  Light  to  Increase 


CIRCULARS 
No. 
259. 
261. 
262. 
263. 
264. 


Winter    Egg    Production. 

Leguminous  Plants  as  Organic  Fertil- 
izer   in    California    Agriculture. 

The   Control   of  Wild   Morning   Glory. 

The  Small-Seeded  Horse  Bean. 

Thinning  Deciduous   Fruits. 


265. 
266. 

267. 

269. 
270. 
272. 

273. 
276. 
277. 

278. 

279. 

281. 


282. 

283. 
284. 
285. 
286. 
287. 
288. 
289. 
290. 
291. 

292. 
293. 
294. 
295. 

296. 

298. 

300. 
301. 
302. 
303. 

304. 
305. 
306. 

307. 
308. 
309. 


Pear  By-products. 

Sewing  Grain  Sacks. 

Cabbage  Growing  in  California. 

Tomato  Production  in  California. 

Preliminary      Essentials      to      Bovine 

Tuberculosis  Control. 
Plant  Disease  and  Pest  Control. 
Analyzing     the     Citrus     Orchard     by 

Means  of   Simple  Tree   Records. 
The  Tendency  of  Tractors  to  Rise  in 

Front;    Causes  and   Remedies. 
An  Orchard  Brush  Burner. 
A  Farm  Septic  Tank. 
California  Farm  Tenancy  and  Methods 

of  Leasing. 
Saving  the  Gophered  Citrus  Tree. 
Home  Canning. 
Head,   Cane,   and   Cordon   Pruning  of 

Vines. 
Olive  Pickling  in  Mediterranean  Coun- 
tries. 
The  Preparation  and  Refining  of  Olive 

Oil   in    Southern    Europe. 
The  Results  of  a  Survey  to  Determine 

the  Cost  of  Producing  Beef  in  Cali- 
fornia. 
Prevention  of  Insect  Attack  on  Stored 

Grain. 
Fertilizing  Citrus  Trees  in  California. 
The  Almond   in   California. 
Sweet  Potato  Production  in  California. 
Milk  Houses  for  California  Dairies. 
Potato   Production  in   California. 
Phylloxera  Resistant  Vineyards. 
Oak  Fungus  in  Orchard  Trees. 
The  Tangier  Pea. 
Blackhead  and   Other  Causes  of  Loss 

of  Turkeys  in  California. 
Alkali  Soils. 

The    Basis   of   Grape    Standardization. 
Propagation   of   Deciduous   Fruits. 
The   Growing  and   Handling  of   Head 

Lettuce  in   California. 
Control     of     the     California     Ground 

Squirrel. 
The    Possibilities    and    Limitations    of 

Cooperative  Marketing. 
Coccidiosis  of  Chickens. 
Buckeye  Poisoning  of  the  Honey  Bee. 
The   Sugar  Beet  in   California. 
A  Promising  Remedy  for  Black  Measles 

of  the  Vine. 
Drainage  on  the  Farm. 
Liming  the  Soil. 
A  General  Purpose  Soil  Auger  and  its 

Use  on  the  Farm. 
American   Foulbrood   and  its   Control. 
Cantaloupe  Production  in  California. 
Fruit  Tree  and  Orchard  Judging. 


The  publications  listed  above  may  be  had  by  addressing 

College  of  Agriculture, 

University  of  California, 

Berkeley,  California. 

12m-3,'28 


